Devices Fabrication with Narrow-Bandgap a-SiGe:H Alloys Deposited by HWCVD

Yueqin Xu; Baojie Yan; Brent P. Nelson; Eugene Iwaniczko; Robert C. Reedy; A. H. Mahan; Howard Branz

doi:10.1557/proc-808-a9.51

Devices Fabrication with Narrow-Bandgap a-SiGe:H Alloys Deposited by HWCVD

Yueqin Xu, Baojie Yan, Brent P. Nelson, Eugene Iwaniczko, Robert C. Reedy, A. H. Mahan, Howard Branz

Materials, Chemical, and Computational Science Research Operations

Research output: Contribution to conference › Paper › peer-review

5 Scopus Citations

Abstract

We incorporate narrow-gap amorphous silicon germanium (a-SiGe:H) alloys grown by hot-wire chemical vapor deposition (HWCVD) into single-junction n-i-p solar cells, and improve both fill factor (FF) and open-circuit voltage (V _oc) by bandgap grading. The Taue bandgap (E_T) of the a-SiGe:H is as low as about 1.25 eV. Previously [1], we obtained a short-circuit current density (J_sc) up to 20 mA/cm² in an n-i-p device incorporating an ungraded 120-nm i-layer of 1.25-eV a-SiGe:H. However, without buffer layers or bandgap profiling, the fill factor was only 38%, likely due to an abrupt bandgap transition and poor hole collection. To overcome these problems, we have used composition bandgap profiling throughout the i-layer and improved both V_oc and FF significantly without any J_sc loss. The solar cell efficiency is improved from 3.55% to 5.85% and V_oc rises from 0.475 to 0.550 eV. This improved single-junction a-SiGe:H solar cell has a quantum efficiency of about 48% at λ=800 nm and about 15% at λ=900 nm. We present details of the bandgap profiling and its effect on device performance.

Original language	American English
Pages	617-622
Number of pages	6
DOIs	https://doi.org/10.1557/proc-808-a9.51
State	Published - 2004
Event	Amorphous and Nanocrystalline Silicon Science and Technology - 2004 - San Francisco, CA, United States Duration: 13 Apr 2004 → 16 Apr 2004

Conference

Conference	Amorphous and Nanocrystalline Silicon Science and Technology - 2004
Country/Territory	United States
City	San Francisco, CA
Period	13/04/04 → 16/04/04

NREL Publication Number

NREL/CP-520-36089

Access to Document

10.1557/proc-808-a9.51

Cite this

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title = "Devices Fabrication with Narrow-Bandgap a-SiGe:H Alloys Deposited by HWCVD",

abstract = "We incorporate narrow-gap amorphous silicon germanium (a-SiGe:H) alloys grown by hot-wire chemical vapor deposition (HWCVD) into single-junction n-i-p solar cells, and improve both fill factor (FF) and open-circuit voltage (V oc) by bandgap grading. The Taue bandgap (ET) of the a-SiGe:H is as low as about 1.25 eV. Previously [1], we obtained a short-circuit current density (Jsc) up to 20 mA/cm2 in an n-i-p device incorporating an ungraded 120-nm i-layer of 1.25-eV a-SiGe:H. However, without buffer layers or bandgap profiling, the fill factor was only 38%, likely due to an abrupt bandgap transition and poor hole collection. To overcome these problems, we have used composition bandgap profiling throughout the i-layer and improved both Voc and FF significantly without any Jsc loss. The solar cell efficiency is improved from 3.55% to 5.85% and Voc rises from 0.475 to 0.550 eV. This improved single-junction a-SiGe:H solar cell has a quantum efficiency of about 48% at λ=800 nm and about 15% at λ=900 nm. We present details of the bandgap profiling and its effect on device performance.",

author = "Yueqin Xu and Baojie Yan and Nelson, {Brent P.} and Eugene Iwaniczko and Reedy, {Robert C.} and Mahan, {A. H.} and Howard Branz",

year = "2004",

doi = "10.1557/proc-808-a9.51",

language = "American English",

pages = "617--622",

note = "Amorphous and Nanocrystalline Silicon Science and Technology - 2004 ; Conference date: 13-04-2004 Through 16-04-2004",

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T1 - Devices Fabrication with Narrow-Bandgap a-SiGe:H Alloys Deposited by HWCVD

AU - Xu, Yueqin

AU - Yan, Baojie

AU - Nelson, Brent P.

AU - Iwaniczko, Eugene

AU - Reedy, Robert C.

AU - Mahan, A. H.

AU - Branz, Howard

PY - 2004

Y1 - 2004

N2 - We incorporate narrow-gap amorphous silicon germanium (a-SiGe:H) alloys grown by hot-wire chemical vapor deposition (HWCVD) into single-junction n-i-p solar cells, and improve both fill factor (FF) and open-circuit voltage (V oc) by bandgap grading. The Taue bandgap (ET) of the a-SiGe:H is as low as about 1.25 eV. Previously [1], we obtained a short-circuit current density (Jsc) up to 20 mA/cm2 in an n-i-p device incorporating an ungraded 120-nm i-layer of 1.25-eV a-SiGe:H. However, without buffer layers or bandgap profiling, the fill factor was only 38%, likely due to an abrupt bandgap transition and poor hole collection. To overcome these problems, we have used composition bandgap profiling throughout the i-layer and improved both Voc and FF significantly without any Jsc loss. The solar cell efficiency is improved from 3.55% to 5.85% and Voc rises from 0.475 to 0.550 eV. This improved single-junction a-SiGe:H solar cell has a quantum efficiency of about 48% at λ=800 nm and about 15% at λ=900 nm. We present details of the bandgap profiling and its effect on device performance.

AB - We incorporate narrow-gap amorphous silicon germanium (a-SiGe:H) alloys grown by hot-wire chemical vapor deposition (HWCVD) into single-junction n-i-p solar cells, and improve both fill factor (FF) and open-circuit voltage (V oc) by bandgap grading. The Taue bandgap (ET) of the a-SiGe:H is as low as about 1.25 eV. Previously [1], we obtained a short-circuit current density (Jsc) up to 20 mA/cm2 in an n-i-p device incorporating an ungraded 120-nm i-layer of 1.25-eV a-SiGe:H. However, without buffer layers or bandgap profiling, the fill factor was only 38%, likely due to an abrupt bandgap transition and poor hole collection. To overcome these problems, we have used composition bandgap profiling throughout the i-layer and improved both Voc and FF significantly without any Jsc loss. The solar cell efficiency is improved from 3.55% to 5.85% and Voc rises from 0.475 to 0.550 eV. This improved single-junction a-SiGe:H solar cell has a quantum efficiency of about 48% at λ=800 nm and about 15% at λ=900 nm. We present details of the bandgap profiling and its effect on device performance.

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Devices Fabrication with Narrow-Bandgap a-SiGe:H Alloys Deposited by HWCVD

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